Derivatives of Somatic Cell Hybrids Which Carry the Human Gene Locus for Nephrogenic Diabetes Insipidus (NDI) Express Functional Vasopressin Renal V2-type Receptors
| Title: | Derivatives of Somatic Cell Hybrids Which Carry the Human Gene Locus for Nephrogenic Diabetes Insipidus (NDI) Express Functional Vasopressin Renal V2-type Receptors |
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| Authors: | Jans, David A.; van Oost, Bernard A.; Ropers, Hilger H.; Fahrenholz, Falk |
| Publisher: | Journal of Biological Chemistry |
| Date Published: | September 15, 1990 |
| Reference Number: | 336 |
The gene responsible for familial vasopressin-resistant nephrogenic diabetes insipidus (NDI) has been localized to a small region of the human X-chromosome (Xq28). A series of hamster lung fibroblast and mouse lymphocyte cell lines carrying fragments of the wild type human X-chromosome was analyzed for vasopressin renal-type V2 receptor expression, to test the hypothesis that the NDI locus may have identity with the V2 receptor gene. V2 receptor binding activity and induction of cAMP production in response to [Arg8] vasopressin (AVP) were exhibited by all cell lines carrying the wild type NDI locus, in contrast to control cell lines. AVP stimulation of cAMP production was concentration-dependent and could be almost completely inhibited by co-incubation with a V2-V1 receptor-specific antagonist. The V2-specific agonist [Mpa1,Val4,Sar7]AVP was as potent as AVP in inducing cAMP production by NDI-DNA-carrying cells, whereas no response was shown to other hormones such as calcitonin, oxytocin (less than 10(-8) M), isoproterenol, or an oxytocin-specific agonist. All results were consistent with the hypothesis that the V2 receptor gene co-localized with the NDI locus, supporting the view that the loci are one and the same.
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This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)
Jans, et al., wanted to see if the gene that produced V2R, the V2R gene, could be located in the Xq28 region of the X chromosome. If it was, then it could be the NDI gene. The authors designed an experiment to help determine if the NDI gene was the V2R gene. They worked with an array of cell lines derived from hamster lungs. Some of these cell lines carried different regions of the human X chromosome. One, cell line 578, carried the entire X human chromosome; one, B17, carried the Xq28 region of the X chromosome; one, B18, carried a fragment of the X chromosome that did not contain the Xq28 region.
Several of these lines were examined to see if they had V2Rs in them. This would indicate that the cell lines also contained the gene responsible for their production, the V2R gene. B17, the cell line that contained the Xq28 fragment of the human X chromosome, indicated the presence of the V2R gene. B18 did not.
The authors could determine this because the B17 cell line showed evidence of binding with AVP when it was introduced into the cell lines. Binding with AVP is a function of V2R. Thus, V2R expression can be attributed to the presence of the Xq28 fragment.
In the principal cells of the kidney collecting duct, once AVP binds with V2R it initiates a molecular sequence that involves the stimulation of the enzyme adenylate cyclase (AdC). AdC in turn stimulates cAMP production. So the authors also examined their cell lines for cAMP production after they introduced AVP into them. Again, B17 evidenced the presence by V2R by stimulating cAMP levels. Cell line B18 did not. The authors extensively tested the B17 line to ensure that its response to AVP was specifically due to V2R. It was.
The results of this study show a clear correlation between V2R expression and the presence in the cell line of the NDI locus-carrying Xq28 human chromosome fragment. This co-mapping of the V2R and NDI location strongly suggests that the V2R gene is probably identical with the NDI locus. In other words, it strongly suggests that mutated V2R genes are responsible for the most common type of congenital NDI.